/*  $NetBSD: _rand48.c,v 1.7 2005/06/12 05:21:27 lukem Exp $    */

/*
 * Copyright (c) 1993 Martin Birgmeier
 * All rights reserved.
 *
 * You may redistribute unmodified or modified versions of this source
 * code provided that the above copyright notice and this and the
 * following conditions are retained.
 *
 * This software is provided ``as is'', and comes with no warranties
 * of any kind. I shall in no event be liable for anything that happens
 * to anyone/anything when using this software.
 */

#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: _rand48.c,v 1.7 2005/06/12 05:21:27 lukem Exp $");
#endif /* LIBC_SCCS and not lint */

#include <assert.h>

#include "rand48.h"
/*lint -e31 -e613*/
unsigned short __rand48_seed[3] = {
    RAND48_SEED_0,
    RAND48_SEED_1,
    RAND48_SEED_2
};
unsigned short __rand48_mult[3] = {
    RAND48_MULT_0,
    RAND48_MULT_1,
    RAND48_MULT_2
};
unsigned short __rand48_add = RAND48_ADD;

void
__dorand48(unsigned short xseed[3])
{
    unsigned long accu;
    unsigned short temp[2];

    assert(xseed != NULL);

    accu = (unsigned long) __rand48_mult[0] * (unsigned long) xseed[0] +
     (unsigned long) __rand48_add;
    temp[0] = (unsigned short) accu;    /* lower 16 bits */
    accu >>= sizeof(unsigned short) * 8;
    accu += (unsigned long) __rand48_mult[0] * (unsigned long) xseed[1] +
     (unsigned long) __rand48_mult[1] * (unsigned long) xseed[0];
    temp[1] = (unsigned short) accu;    /* middle 16 bits */
    accu >>= sizeof(unsigned short) * 8;
    accu += __rand48_mult[0] * xseed[2] + __rand48_mult[1] * xseed[1] + __rand48_mult[2] * xseed[0];
    xseed[0] = temp[0];
    xseed[1] = temp[1];
    xseed[2] = (unsigned short) accu;
}
/*lint +e31 +e613*/
